DE946323C - Method for joining two turned parts made of different metallic materials - Google Patents

Description

Method for connecting two turned parts made of different metallic materials Materials To turn parts for machines or construction purposes without the help of special To firmly connect holding members, for example of machine elements, to one another, Shrink-fitting can be used. There are also other methods for example casting on or around or soldering and plating are known. When shrinking, there are dimensional changes caused by temporary temperature differences advantageously used to produce a firm bond or connection. Included the procedure is usually such that one part of the later composite body is heated or the other part was hypothermic or both measures were used at the same time.

It is also no longer new, an auxiliary body for shrinking to use, whose metal mass is large enough to compensate for temperature too quickly prevented. The auxiliary body, which advantageously consists of individual segments, is before hypothermia or heating inserted into the body that with another Body through Shrinkage is to be connected. Only then does it take place the warming or subcooling:.

It has been shown, however, that the previous shrinking methods do not are sure to withstand all stresses and that in the case of composite bodies, which are subject to a change in temperature, for example rewarming loosening of the connection may occur.

The invention is concerned with an opposite of the previous general applied measures much simpler procedures to bring about solid, perfect connections between turned parts made of different metallic materials, preferably for storage purposes or also generally for sliding machine parts, in particular for pistons of internal combustion engines. The invention is such. B. the task solved to produce composite pistons or composite bearings without rewarming the aforementioned disadvantage of loosening becomes apparent.

The good sliding properties of gray cast iron cause again and again To form pistons whose shaft is made of this material, while the rest Parts of the piston, such as the ring part, the piston head and the piston pin bosses, should be made of light metal to reduce the weight of the piston. In quite a variety of ways these are made of two different metals existing parts have so far been connected to each other. The measures used and means, however, have by no means fully satisfied because of the piston either became too heavy or its lifespan could not yet be made 'long enough, to be of practical importance. It has already succeeded, through application certain pouring or pouring methods using intermediate layers in conjunction with the utilization of the shrinkage effect to produce composite pistons, which the plugged Already getting closer to the goal. However, the manufacturing cost is by this method still too high.

The invention is based on the fact that bearing materials without sufficient lubricating film at a certain load for seizure on the rotating Wave incline and uses the knowledge of the creation of such for storage purposes adverse effect beneficial for establishing a firm and secure connection between two different types of metallic turned parts.

According to the invention, one of the two rotating parts leads, while "this in the axial direction take their final position to each other or after they -took this position when shrinking on the other rotating part a twisting motion.

“In order to carry out the. Procedure, the two will turn Parts .: so undersized that one part over the other only when it is present a temperature difference can be pushed. The warming is directed depending on the metallic material used and is used in the case of welding Chosen between gray cast iron and light metal at about zoo to 35o ° C. One of both Rotary parts are preferably secured against rotation. This is advantageous an adjustable friction or slip clutch or - also the arrangement of disks. When a certain torque is exceeded, the relative movement of the two Parts canceled.

The invention is based on the embodiment shown in the drawing explained, which illustrates the shrink-fitting of two cylindrical parts in the scheme. In a lathe chuck a, a piston inner part b made of light metal is for eirW, internal combustion engine held and by means of piston pin c against rotation secured. A gray cast iron sleeve d, which is inseparable from the inner part b is to be connected is housed in a socket e, which is heated. To the Electrical resistance bodies are used for heating. The bushing e is on a lathe tailstock g attached, which extends along the lathe bed in the axial direction to the piston axis can move.

When heated, the gray cast iron sleeve d initially expands and can therefore be easily pushed over the cold inner piston part b, which is set in rotating motion. During cooling and the resulting heat transfer to the piston inner part b, the contact pressure between the two shrink parts b and d grows more and more as the shrinkage temperature decreases, so that the gray cast iron sleeve d sits more firmly on part b.

To the resulting shrink connection, however, there is a rotating one Relative movement of the two parts to each other also a metallic connection as a result of the tearing of the oxide film, so that a much stronger one Connection of the two parts to be connected occurs than when it is at rest Shrinking to one another. The connection takes place after the oxide film has been destroyed by fretting and leads to welding. The torque - increases a lot strong. A centrifugal mass h can, however, be used to transfer the living force can be increased significantly. When a certain torque is exceeded a clutch i releases the retaining device of the gray cast iron sleeve d. The clutch can be designed as a slip clutch or act as a breakaway clutch, the Shear off the protruding retaining pin k on the gray cast part d. The release of the clutch must be set in such a way that the binding is flawless over the entire circumference is guaranteed not only by shrinking but also by seizing.

The sleeve e, which includes the sleeve d to be welded on, serves as a furnace. The heating can be in any known manner, preferably such as mentioned, be done electrically or by gas. The part to be shrunk can also in a special oven, separate from the device to connect of the two parts.

Claims (2)

PATENT CLAIMS: i. Method for connecting two turned parts from different metallic materials with one another by shrinking them on, characterized in that that one of the two rotating parts, while -this is its final one in the axial direction Take up position to each other or after they have taken up this position, when shrinking executes a rotary movement with respect to the other rotating part. 2. The method according to claim i, characterized in that when a certain torque is exceeded the relative movement of the two parts is canceled, for example by a self-releasing clutch. Publications considered: German Patent No. 686 21q ..